Yet another study shows the superiority of lower-carb eating over low-fat

I came across this report yesterday. It concerns a study presented at the American Heart Association meeting in San Diego this week. From the report it appears that overweight individuals were randomised to one of two diets for 6 months (along with moderate exercise).

‘low-carb’: 30, 40, 30 per cent of calories from carbohydrate, fat and protein respectively

‘low-fat’: 55, 30, 15 per cent of calories from carbohydrate, fat and protein respectively

Those on the low-carb diet lost a lot more weight than those on the low-fat diet – about 29 lbs (13 kg) v 19 lbs (8.5 kg).

The study participants were also tested for a measure of health in the cardiovascular system known as ‘flow mediated dilatation’ (FMD). Here’s how the report I’ve linked to describes this test and the results:

In order to evaluate the health of the participants’ blood vessels before and after the weight loss program, the researchers conducted a blood flow test by constricting circulation in the upper arm for five minutes with a blood pressure cuff. With this type of test, when the cuff is released, a healthier artery will expand more, allowing more blood to flow through the artery. The researchers measured how much blood reached the fingertips before, during, and after the constriction of the artery. Stewart (Kerry J Stewart – professor of medicine at the Johns Hopkins University School of Medicine) says this test can give an indication of the overall health of the vascular system throughout the body. The researchers found that the more belly fat a person had lost, the greater the blood flow to the finger, signalling better the function of the artery.

Professor Stewart goes on to say that:

Our study demonstrated that the amount of improvement in the vessels was directly linked to how much central, or belly fat, the individuals lost, regardless of which diet they were on. This is important since there have been concerns that a low-carb diet, which means eating more fat, may have a harmful effect on cardiovascular health. These results showed no harmful effects from the low-carb diet.

Many studies have now pitted low-fat against low-carb diets in terms of weight loss and disease markers, and low-carb reigns victorious. Unless, of course, you’d prefer to discount all this good, clinical evidence in humans in favour of experiments done in genetically manipulated mice. See here.


10 Responses to Yet another study shows the superiority of lower-carb eating over low-fat

  1. Jeremy 16 March 2012 at 4:00 pm #

    Could you please post the link to the actual study?

  2. TerryJ 16 March 2012 at 4:31 pm #

    The link is in the first line ‘this report’ is a clickable link.

  3. jake3_14 16 March 2012 at 9:44 pm #

    The alleged low-carb diet really isn’t. My understanding is that for weight loss, a healthy LC diet has a max of 10% carbs, with no grains. Even in the maintenance phase, a healthy low-carb diet is a max of 20% carbs (100g), with no grains. In the study’ LC diet, “up to 30 percent of calories came from carbs such as bread, pasta and certain fruits…” It’s amazing that even with this bastardized version of a LC diet in the study, LC still came out ahead in terms of total weight loss.

    I wonder if the study analyzed fat mass loss, which is what is more important than total weight loss.

  4. tess 17 March 2012 at 12:32 am #

    that’s a nice aspect you don’t hear about often –thanks!

  5. helen 17 March 2012 at 2:23 am #

    well low carb really means, lots of protein & fats more veggies of the leafy green variety, less sugar laddened fruits and no or minimal starchy veggies & no or very limited grains. It is interesting to know that a serve of pasta or rice is half a cup – cooked & 2 sandwich size slices of bread is considered one serve…….how much more than this does everyone who eats this stuff have??

  6. Paul Devine 17 March 2012 at 12:16 pm #

    No mention of randomization or blinding- is this trials quality blighted by biases and should be ignored?

    To be honest I haven’t looked at the trial itself but I wanted to make the point that this study is reported “as is” and not subject to the same level of critical appraisal the previous red meat study was.

    Do we only look for fault when the report differs from our views and what we want to hear?

  7. Dr John Briffa 17 March 2012 at 1:20 pm #


    Do we only look for fault when the report differs from our views and what we want to hear?

    That’s a valid point you raise, except for the fact that here all we have is a report of the study to go on (so limited potential for critique), where as in the case of the red meat study we have access to the full text of the published article.

  8. jake3_14 19 March 2012 at 11:16 pm #

    My understanding is that there are two major types of food questionnaires used in eating studies: food frequency questionnaires and dietary logs. The problems with food frequency questionnaires are legion and well-documented, as you allude to. Dietary logs are a bit better, as participants are required to log, in detail, the amount and type of food they eat for a specific period of time on a daily basis. That’s what I do with my nutrition software, and that practice gives me a fairly accurate picture of my intake. Of course, the best monitoring, a locked metabolic ward study, is extremely expensive to do correctly, not to mention finding a valid study population in reasonable health (but not model) that can be locked up for an extended period of time.

  9. PJ 20 March 2012 at 2:48 am #

    “Do we only look for fault when the report differs from our views and what we want to hear?”

    Actually, Paul, the reason I am biased against the results of this “scientific study” is that it is probably the least scientific of all study methods. They used questionnaires every four years and depended on peoples memories (and honesty) to answer lifestyle and diet questions. These “studies” may be a starting point upon which to develop a hypothesis, but you can by no means derive absolute scientific conclusions from them. Any time I see a questionnaire based “study”, I know that the conclusions reached by these “scientists” are highly suspect and could have been interpreted many different ways. Am I biased? Yes, against questionnaire studies.

  10. Keith C. 20 March 2012 at 6:54 pm #

    There are quite a few things I feel that make this a near worthless study. First, this does not appear to be a controlled inpatient, ward study. As I’m sure we can all agree on, non-controlled studies like these are hardly reliable when it comes to the accuracy of reported caloric intake.

    Also, they talk about weight loss, but shouldn’t we be more concerned with the type of weight being lost (e.g. body composition)? I am not overly concerned with the amount of water lost (typically greater in low carb diets) but I am concerned in the amount of fat versus lean muscle tissue lost…
    For example, in this study it shows that although short term weight loss advantages go in the favor of keto style diets, pay attention to the percentages of weight lost (keto is very high water loss whereas mixed diet shows higher fat loss percentages)
    Here is an actual controlled study that indicates there were no real advantages to a keto-style diet in relationship to mental state, satiety, or body composition.

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